Structured lighting material, method to generate incoherent luminescence and illuminator

ABSTRACT

A structured lighting material, an illuminator, and the method to generate incoherent luminescence wherein luminescent intensity increases superlinearly when excitation energy applied thereto through electron beam, electric charge, electric field or the like exceeds a threshold. In the present invention, the structured lighting material is easily made to have a minute uneven surface. This invention enables high-efficient lighting devices, sensors and memories owing to the superlinearity.

BACKGROUND OF THE INVENTION

[0001] 1) Field of the Invention

[0002] The present invention relates to a structured lighting material,method to generate incoherent luminescence and an illuminator each ofwhich emits light when energy is applied thereto from the external.

[0003] 2) Description of the Related Art

[0004] So far, various luminescent devices have been developed whichemit light in response to energy such as electron beam being appliedthereto from the external. For example, a luminescent device has beenknown as having some conventional structured lighting material. Thepresent invention concerns a specific structured lighting material to bedescribed below. The luminescent device has come into widespread use indisplay applications using a cathode-ray tube, a projection tube or thelike (cf. Phosphor Handbook, by S. Shionoya and W. M. Yen, CRC Press,Boca Raton, Fla., 1998). Diverse experiments on structured lightingmaterials including luminescent devices have been made up to now.

[0005] A description will be given hereinbelow of a conventionalluminescent device with reference to FIGS. 11(A) and 11(B). Aluminescent device comprises a metal-made substrate (base) 102 and aluminescent unit 103 made by placing a phosphor on the substrate 102 inthe form of a layer.

[0006] In such a configuration, the luminescent device emits light whenthe host of a phosphor constituting the luminescent unit 103 is excitedby electric energy such as electron beam, electric charge or electricfield applied from the external. Thus, the luminescent device canconvert the inputted electric energy (excitation energy) intoluminescence to be outputted.

[0007] Although the luminescence or emission intensity of theluminescent device generally increases monotonically with an increase inan excitation energy inputted from the external, the degree of increaseis prone to drop if the excitation energy quantity exceeds an energyquantity; if the excitation energy quantity further increases, theluminescent intensity reaches a saturation or decreases (cf. PhosphorHandbook, by S. Shionoya and W. M. Yen, CRC Press, Boca Raton, Fla.,1998, p.489-p.498). When a correlation between electron beam current(current value) A acting as excitation energy and luminescence intensityare shown on a log-log graph and the inclination (which will be referredto hereinafter as an “input-output differential variation”) θ[=Δlog(I)/Δ log(A)] of the line representing this correlation assumes apositive value, it is referred to as a monotonic increase.

[0008] The input-output differential variation of the conventionalluminescent device is apt to get worse as the input energy such aselectron beam increases.

SUMMARY OF THE INVENTION

[0009] The present invention has been developed in consideration of sucha situation, and it is therefore an object of the invention to provide astructured lighting material wherein luminescent intensity increasessuperlinearly when excitation energy based on electron beam, electriccharge or electric field exceeds a threshold.

[0010] In the present invention, the term “superlinearly” signifies thatthe input-output differential variation θ increases when applied energyexceeds a threshold. In most cases, when the applied energy is below thethreshold, the input-output differential variation θ assumes lessthan 1. On the other hand, it becomes 1 or more when the applied energyis above the threshold.

[0011] For this purpose, a structured lighting material according to thefirst aspect of the present invention is characterized by comprising aluminescent unit wherein the intensity of incoherent luminescenceincreases superlinearly when energy applied in a non-contact mannerexceeds a threshold.

[0012] This arrangement, wherein the luminescent intensity of theluminescent unit increases superlinearly when the electric energy givenin a non-contact manner exceeds the threshold, can be incorporated intoa wide range of applications. For example, the application to varioustypes of illuminations is feasible owing to its high-efficientluminescence. As a further advantage, it is also applicable to detectionequipment, alarm equipment or the like because the magnitude of theelectric energy can be monitored from the luminescence intensity of theluminescent unit. Furthermore, the application to memories or varioustypes of control devices becomes feasible because the luminescentintensity varies rapidly around a threshold so that the variation of theluminescent intensity is extracted as on/off signals in a state wherereference is set to the threshold.

[0013] In accordance with a further feature of the present invention, inthe structured lighting material stated above as the first aspect of theinvention, the luminescent color of the luminescent unit varies as theinput energy increased beyond the threshold.

[0014] This provides easy visual confirmation of the variation of thestate of the luminescent unit.

[0015] In accordance with a further feature of the present invention, inthe structured lighting material stated above as the first aspect of theinvention, the energy is electric energy originating from any one ofelectron beam, electric charge and electric field.

[0016] This allows an energy applying means in a conventional structuredlighting material (such as a conventional luminescent device) to beavailable as it is.

[0017] In accordance with a further feature of the present invention, inthe structured lighting material stated above as the first aspect of theinvention, the luminescent part has a non-electrical conductiveproperty.

[0018] This can provide advantages of securing electrification propertyof the luminescent unit, generating rapid increase of the luminescentintensity beyond a threshold and effective variation of luminescentcolor, and developing such variation in the intensity and color of theluminescent unit with low applied energy.

[0019] A structured lighting material according to the second aspect ofthe present invention is characterized by comprising a luminescent unitwhich shows a non-electrical conductive property and has a microscopicor minute uneven surface, wherein the luminescent intensity increasessuperlinearly when energy applied to the minute uneven surface in anon-contact manner exceeds a threshold.

[0020] The effects similar to those of the structured lighting materialaccording to the first aspect of the invention are attainable, becausethe luminescent intensity of the luminescent unit increasessuperlinearly and the luminescent color of the luminescent part varies,when electric energy applied to the minute uneven surface in anon-contact manner exceeds the threshold.

[0021] In addition, the luminescent intensity higher than that of aconventional structured lighting material is assured, which realize ahigh-output illuminator.

[0022] Still additionally, the requirement for the luminescent unit isonly the realization of the minute uneven surface, and various kinds ofknowledge concerned with the conventional structured lighting materialscan be put directly to practical use.

[0023] In accordance with a further feature of the present invention, inthe structured lighting material stated above as the second aspect ofthe invention, the minute uneven surface is formed in a manner that thethickness of the luminescent unit is made non-uniform.

[0024] This allows easy formation of the minute uneven surface simply bymaking the thickness of the luminescent unit non-uniform. The effectssimilar to those of the structured lighting material according to thesecond aspect of the invention are attainable.

[0025] In accordance with a further feature of the present invention, inthe structured lighting material stated above as the second aspect ofthe invention, the minute uneven surface has high and low portionsrespectively corresponding to maximum and minimum thicknesses of theluminescent unit, and the maximum thickness is set to be three or moretimes said minimum thickness.

[0026] This makes the unevenness of the luminescent unit surfaceeffective, and the effects similar to those of the above-mentionedstructured lighting material is assured.

[0027] In addition, in accordance with a further feature of the presentinvention, in the structured lighting material stated above as thesecond aspect of the invention, the minute uneven surface has high andlow portions respectively corresponding to maximum and minimumthicknesses of the luminescent unit, and the maximum thickness is set tobe ten or more times said minimum thickness.

[0028] This makes the unevenness of the luminescent unit surfaceeffective, and the effects similar to those of the above-mentionedstructured lighting material is more assured.

[0029] Still additionally, in accordance with a further feature of thepresent invention, in the structured lighting material stated above asthe second aspect of the invention, the minimum thickness of theluminescent unit is not more than 500 μm.

[0030] This makes the unevenness of the luminescent unit surfaceeffective, and the effects similar to those of the above-mentionedstructured lighting material is assured.

[0031] Furthermore, in accordance with a further feature of the presentinvention, in the structured lighting material stated above as thesecond aspect of the invention, the minimum thickness of the luminescentunit is not more than 50 μm.

[0032] This makes the unevenness of the luminescent unit surfaceeffective, and the effects similar to those of the above-mentionedstructured lighting material is more assured.

[0033] Still moreover, in accordance with a further feature of thepresent invention, in the structured lighting material stated above asthe second aspect of the invention, an inclination angle (slope angle)of an uneven surface of a local site is in a range from 30 degrees to150 degrees.

[0034] This makes the unevenness of the luminescent unit surfaceeffective, and the effects similar to those of the above-mentionedstructured lighting material is assured.

[0035] Yet moreover, in accordance with a further feature of the presentinvention, in the structured lighting material stated above as thesecond aspect of the invention, an inclination angle of an unevensurface of a local site is in a range from 50 degrees to 130 degrees.

[0036] This makes the unevenness of the luminescent unit surfaceeffective, and the effects similar to those of the above-mentionedstructured lighting material is more assured.

[0037] Furthermore, in accordance with a further feature of the presentinvention, in the structured lighting material stated above as the firstaspect of the invention, the luminescent unit is made of inorganicmaterial.

[0038] Accordingly, this realizes less degradation while the energy isapplied thereto.

[0039] Still furthermore, in accordance with a further feature of thepresent invention, in the structured lighting material stated above asthe first aspect of the invention, the luminescent unit is adhered on asubstrate.

[0040] This allows the luminescent unit to be formed in a stablecondition.

[0041] Yet furthermore, in accordance with a further feature of thepresent invention, in the structured lighting material stated above asthe first aspect of the invention, the luminescent unit is adhered on asubstrate without using water-soluble fixing agent.

[0042] This secures the electrification property of the luminescentunit, and the effects similar to those of the above-mentioned structuredlighting material are attainable.

[0043] Moreover, in accordance with a further feature of the presentinvention, in the structured lighting material stated above as the firstaspect of the invention, the luminescent unit is adhered on thesubstrate in a manner of facilitating electrification.

[0044] This secures the electrification property of the luminescentunit. The effects similar to those of the above-mentioned structuredlighting material are attainable.

[0045] Still moreover, an illuminator according to the third aspect ofthe present invention is characterized by comprising the structuredlighting material according to the first or second aspects of thepresent invention.

[0046] This provides efficient luminescence for supplied energy.

[0047] In addition, a method to generate incoherent luminescenceaccording to the fourth aspect of the present invention is characterizedby applying energy more than a threshold to the structured lightingmaterial including a luminescent unit wherein the intensity ofincoherent luminescence increases superlinearly when energy applied in anon-contact manner exceeds the threshold.

[0048] This offers the effects similar to those of the structuredlighting materials according to the first and second aspects of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIGS. 1(A) and 1(B) are illustrations of a configuration of aluminescent device (structured lighting material) according to anembodiment of the present invention, and FIG. 1(A) is an illustrativeplan view while FIG. 1(B) is an illustrative enlarged cross-sectionalview taken along a line X1-X1 of FIG. 1(A);

[0050] FIGS. 2(A) and 2(B) are illustrations of another configuration ofa luminescent device (structured lighting material) according to anembodiment of the present invention, and FIG. 2(A) is an illustrativeplan view while FIG. 2(B) is an illustrative enlarged cross-sectionalview taken along a line X3-X3 of FIG. 2(A);

[0051]FIG. 3 is a side elevation view illustratively showing aconfiguration of an experimental equipment according to the firstexample of the present invention;

[0052]FIG. 4 is an illustration of measurement results of an experimenton the current dependency of luminescent intensity in a luminescentdevice (structured lighting material) according to the first example ofthe present invention and a conventional luminescent device;

[0053]FIG. 5 is an illustration of measurement results of an experimenton the current dependency of luminescent intensity in a luminescentdevice (structured lighting material) according to the second example ofthe present invention and a conventional luminescent device;

[0054]FIG. 6 is an illustration of results of measurement of aluminescent spectrum of a luminescent device (structured lightingmaterial) according to the second example of the present invention;

[0055]FIG. 7 is an illustration of measurement results of an experimenton the current dependency of luminescent intensity in a luminescentdevice (structured lighting material) according to the third example ofthe present invention;

[0056]FIG. 8 is an illustration of measurement results of an experimenton the current dependency of luminescent intensity in a luminescentdevice of a comparative example in contrast with the present invention;

[0057]FIG. 9 is an illustrative view showing a configuration of an imagetube (illuminator) using a luminescent device (structured lightingmaterial) as the first application example of the present invention;

[0058] FIGS. 10(A) and 10(B) are illustrations of a configuration of acathode-ray lamp (illuminator) using a luminescent device (structuredlighting material) as the second application example of the presentinvention, and FIG. 10(A) is an illustrative cross-sectional view whileFIG. 10(B) is an illustrative view showing a cross section perpendicularto a cross section of FIG. 10(A); and

[0059] FIGS. 11(A) and 11(B) are illustrations of a configuration of aconventional luminescent device (structured lighting material), and FIG.11(A) is an illustrative plan view while FIG. 11(B) is an illustrativecross-sectional view taken along a line X2-X2 of FIG. 11(A).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] Embodiments of the present invention will be describedhereinbelow with reference to the drawings.

[0061] FIGS. 1(A), 1(B), 2(A) and 2(B) are illustrations of aluminescent device according to an embodiment of the present invention.FIGS. 1(A) and 1(B) are illustrations of a configuration thereof, andFIG. 1(A) is an illustrative plan view while FIG. 1(B) is anillustrative enlarged cross-sectional view taken along a line X1-X1 ofFIG. 1(A), and FIGS. 2(A) and 2(B) are illustrations of anotherconfiguration thereof, and FIG. 2(A) is an illustrative plan view whileFIG. 2(B) is an illustrative enlarged cross-sectional view taken along aline X3-X3 of FIG. 2(A).

[0062] As FIGS. 1(A) and 1(B) show, this luminescent device (structuredlighting material) 1 comprises a metal-made (for example, copper-made)substrate 2 and an insulation (non-electrical conductive) luminescentunit 3 adhered on the substrate 2, and grooves 4 are made in alattice-like fashion in the luminescent unit 3.

[0063] A luminescent material for the formation of the luminescent unit3 requires only a non-electrical conductive property, and materialsapplicable to the conventional luminescent devices are also applicableas the luminescent material, for example, television red phosphor(Y₂O₂S:Eu, Tb), blue phosphor (SrHfO₃:Tm) or the like put on the market.

[0064] Incidentally, in this case, the insulation (non-electricalconductive) property signifies that the electrical resistivity is notbelow 10⁶ Ω·cm. In particular, as the luminescent material, a materialof the electrical resistivity R equal to or above 10⁸ Ω·cm (R≧10⁸ Ω·cm)is preferable.

[0065] In addition, although the luminescent material for the formationof the luminescent unit 3 can be organic or inorganic luminescentmaterials, the inorganic luminescent material is more preferable becauseof high stability (less degradation) during input of electric energythereto (particularly, during the input of electron beam).

[0066] As a preferred example of the luminescent material for theformation of the luminescent unit 3, a description will be givenhereinbelow of a non-electrical conductive inorganic luminescentmaterial. As the inorganic luminescent material, conventional materialsfor use in a wide range of applications, such as display tubes,luminescent lamps, X-ray/radioactive ray detective devices andluminescent display tubes, are available.

[0067] A typical example of the inorganic luminescent material is aninorganic phosphor, and the inorganic phosphor is produced in the formof powder in the usual way and it is conventional practice to form theluminescent unit 3 by adhering this phosphor powder to the substrate 2.An insulating film or the like can be properly interposed between themetal-made plate (substrate) 2 and the powder layer (luminescent unit)3.

[0068] Furthermore, a significant feature of this structured lightingmaterial is that grooves 4 are made in the luminescent unit 3 in alattice-like fashion as mentioned above. For easy formation of thegrooves 4, for example, after the luminescent unit 3 is formed in amanner that the phosphor powder is adhered onto the substrate 2according to a method which will be described later, the luminescentunit 3 is whittled with a sharp-edged tool such as a tip portion of apincette. In this case, as FIG. 1(A) shows, the grooves 4 includesvertical grooves 4 a made in vertical directions and horizontal grooves4 b made in horizontal directions.

[0069] The luminescent unit 3 is made to emit light when receivingelectric energy such as electron beam, electric charge or electric fieldfrom the external in a non-contact manner (without coming into directcontact with the energy source), and in this connection, the inventorshave found, in process of diverse experiments on the structured lightingmaterial, that if crests, grooves, projections or the like arranged in alattice-like configuration, or a combination of more than oneconfiguration of them, are made on the luminescent unit 3 so that aminute uneven surface is formed on a surface of the luminescent unit 3,a new luminescent spectrum component occurs in the vicinity of localuneven sites (high and low portions) when energy applied to the unevensurface of the luminescent unit 3 exceeds a threshold; in consequence,the luminescent intensity increases. Furthermore, the luminescenceintensity from the output light of the luminescent unit 3 increasessuperlinearly with respect to the applied energy. Even the luminescentcolor varies as the energy (excitation energy) applied to theluminescent unit 3 exceeds the threshold; the luminescent color variesin accordance with the energy that goes above or below the threshold. Inthis case, usually, the light emitted from the luminescent unit 3 isincoherent. The term “incoherent (non-coherent)” signifies that lightsemitted from two arbitrary points of the luminescent unit do nointerfere with each other, and it is easily distinguished from coherentlight such as laser light.

[0070] The minute uneven surface signifies fabrication including asurface having very small projections (convexities, high portions) andvery small holes (concavities, low portions), or having unevencross-section such as a wave-like (corrugated) or rectangle-arrangedcross-section, with the uneven cross-section comprisingprojections/small holes, waves, rectangles or the like being arrangedregularly or irregularly.

[0071] Preferably, this minute uneven surface satisfies the conditionwhich will be defined later in the claim (any one of claims 6 to 12). Ingeneral, the minute uneven surface comprises a large number of highportions such as poly-sided pyramid (including trigonal pyramid,quadrangular pyramid) or cones, frustums (including frustums of trigonalpyramid, frustums of quadrangular pyramid or frustums of cone), orpseudo-cones wherein head portions have mountain-like or hemisphericalshapes and a large number of low portions as opposed to these highportions. It is particularly preferable to employ regular/irregularpattern comprising a large number of cones or pseudo-cones wherein headportions have mountain-like or hemispherical shapes. These high and lowportions can also be arranged regularly or irregularly. Moreover, it isalso possible that the low portions are arranged to overlap continuouslywith each other for making a groove-like configuration, or that the highportions are made in a continuously overlapping fashion to provide amountain-range-like configuration.

[0072] The layer thickness of the luminescent unit 3 is not particularlyspecified before its surface is made uneven. Any thickness is acceptableprovided so the formation of the minute uneven surface exists. However,preferably, the layer thickness ranges from 100 μm to 3000 μm. If theunevenness on the uneven surface is too minute (if the difference inheight between the high and low portions is too small), the prominentincrease of luminescence is hardly observed. For this reason, the localvariation up to 20 μm is disregarded. In other words, it is preferablethat the difference in height between the high and low portions is setto be above 20 μm.

[0073] Although the mechanism of change of the luminescent characterunder the non-contact application of the energy to the structuredlighting material with the minute uneven surface does not yet reachdefinite understanding, it is inferred that the following mechanismwhich may cause the luminescent intensity to increase superlinearly whenexcitation energy exceeds a threshold.

[0074] When energy such as electron beam irradiation is provided to theluminescent unit 3, the host of a luminescent material forming theluminescent unit 3 is so excited that many electron-hole pairs aregenerated in the luminescent material. At this time, the electron-holepairs move with energy toward the luminescence centers in theluminescent material, thereby developing the luminescence by theirrecombination. This is a luminescence mechanism taking place in anordinary structured lighting material (luminescent device).

[0075] In the present invention, since the phosphor powder layer(luminescent unit) 3 shows a non-electrical conductive property, thepowder layer 3 falls into an electrified condition. In this case, if aminute uneven surface with non-uniform thickness is made on theluminescent unit 3 in such a manner as to make the grooves 4 in theluminescent unit 3 as mentioned above, then the electric field of theluminescent unit 3 becomes non-uniform, which leads to a locally highelectric field in the vicinity of the uneven surface. The uneven surfacecan induce local electric field concentration. In this case, the pointis that the minute uneven surface of the luminescent unit 3 is anyfabrication to enable non-uniformity of electric field.

[0076] Thus, in a case in which the luminescent unit 3 is extremelyeasily electrified, more electrons are stored in the vicinity of thesurface of the luminescent unit 3 as the energy applied from theexternal becomes larger. Therefore, a local strong electric fieldaccordingly takes place in the vicinity of the surface of theluminescent unit 3.

[0077] When the strength of this electric field exceeds a threshold(that is, when the applied energy exceeds a threshold), electrons and/orholes caught at a deep level in the host of the luminescent unit aredischarged into conduction bands and/or valence bands in thePoole-Frenkel process or the Fowler-Nordheim process or the both andaccelerated by the strong electric field to excite the luminescencecenters, and/or applying an extremely strong electric field reduces thewidth of the barrier confining the electrons and/or holes to causecarrier injection in tunnel processes so that the carriers areaccelerated by the strong electric field to excite the luminescencecenters.

[0078] Furthermore, the luminescence centers can be not only impuritiesrepresenting simple metals/transition metals doped on purpose but alsopotential point defects, line defects, plane defects or surface defectsoccurring in the manufacturing process for the luminescent unit 3.Accordingly, in addition to the occurrence of carriers by the energysuch as electron beam excitation, strong electric field takes place byminute uneven configuration in which the thickness of the luminescentunit 3 is made non-uniform in a manner that the grooves 4 are made inthe non-electrical conductive luminescent unit 3 as described above.This strong electric field thus create many carriers. Furthermore, itcan be considered that the carriers increase the intensity of theluminescence from the luminescence centers doped intentionally andfurther increases the intensity of the luminescence from theluminescence center which is made by potential defects/impuritiesintroduced in the manufacturing processes. From this consideration, itcan be considered that the luminescent intensity of the luminescent unit3 increases superlinearly when the energy given through the use ofelectron beam irradiation or the like exceeds a threshold.

[0079] A description will be given hereinbelow of a threshold of inputenergy for a sudden change of the luminescence character of theluminescent unit 3. This threshold depends upon various kinds ofconditions of the luminescent unit 3. The threshold can be set at adesired value through the adjustment of these conditions; luminescentmaterials, synthesis conditions [kind and quantity of flux, firingtemperature, firing time, time taken for a cooling temperature,after-treatment (grinding method, washing method, drying method, andothers)], manners for applying phosphor powder to the substrate 2 (theway for the adhesion on the substrate 2) and additional treatmentthereon, degree of unevenness in the minute uneven surface (that is,non-uniformity in thickness, and specifically, the number of grooves 4,shape, depth, surface unevenness (roughness) of the luminescent unit 3,or the like).

[0080] In the example shown in FIGS. 1(A) and 1(B), each of the verticalgrooves 4 a and each of the horizontal grooves 4 b are formed to havewidth Wa and Wb, respectively, and the vertical grooves 4 a and thehorizontal grooves 4 b are spaced by Da and Db from each other,respectively, and located at equal intervals. In this case, these widthWa, Wb and spaces Da, Db are set at approximately 1 mm. In addition, fora depth d of the grooves 4, in a case in which the luminescent unit 3has a thickness t, it is preferable that the maximum thickness (in thiscase, the thickness of a portion at which no groove 4 exists) t of theluminescent unit 3 is set at three or more times [t≧3(t−d)] the minimumthickness (in this case, the thickness at a portion at which the groove4 exists) t₁(=t−d). More preferably, the maximum thickness t is ten ormore times [t≧10(t−d)] the minimum thickness t₁.

[0081] In particular, at high and low portions adjacent to each other,it is preferable that the maximum thickness t is set at three or moretimes the minimum thickness t₁, more preferably, ten or more times.

[0082] Still additionally, preferably, the depth (the height of the highportion or convexity) d is set at 20 μm or more (d≧20 μm) in a view ofsecuring the luminescence performance of the present invention.

[0083] From the viewpoint of making effective the unevenness of thesurface of the luminescent unit 3, in the example shown in FIGS. 1(A)and 1(B), it is preferable that the minimum thickness t₁ is set to be500 μm or below (t₁≦500 μm), more preferably, 70 μm or below (t₁≦70μm)), and most preferably, 50 μm or below (t₁≦50 μm). Moreover, theminimum thickness t₁ is possible to be 0.01 μm or more (t₁≧0.01 μm), 0.5μm or more(t₁≧0.5 μm)), and also, 1 μm or more (t₁≧1 μm).

[0084] In addition, in the example shown in FIGS. 1(A) and 1(B),preferably, the maximum thickness t is 100 μm or more (t≧100 μm), andmore preferably, 200 μm or more (t≧200 μm). Moreover, the maximumthickness t is possible to be 3 mm or below (t≦3 mm), or 500 μm or below(t≦500 μm).

[0085] From the same viewpoint of making effective an unevenness of thesurface of the luminescent unit 3, in the example shown in FIGS. 1(A)and 1(B), it is preferable that the angle α of inclination (slope) of anuneven surface is in a range from 30 degrees to 150 degrees, morepreferably, in a range from 50 degrees to 130 degrees, and furtherpreferably, in a range from 50 degrees to 88 degrees. This inclination(slope) angle α of the uneven surface signifies an angle of a sidesurface (a surface other than a vertex surface and a base) of the unevensite with respect to a plane parallel to the substrate.

[0086] The layer thickness of the luminescent unit 3 and the aforesaidparameters of the uneven surface can easily be measured with anon-contact type three-dimensional analysis apparatus (for example, alaser microscope). For example, the employment of an image measurementCNC three-dimensional analysis apparatus manufactured by MITUTOYO Co.,Ltd. or an ultra-depth shape measuring microscope manufactured byKEYENCE Co., Ltd. enables the measurements of the maximumthickness/minimum thickness of one uneven surface and the inclinationangles of uneven surfaces.

[0087] As mentioned above, no limitation is imposed in shape on thegrooves 4 as long as it produces non-uniform thickness of theluminescent unit 3 for a minute uneven surface in the luminescent unit3.

[0088] For example, the parameters Wa, Wb, Da and Db are not limited tothe above-mentioned values. Moreover, the luminescent unit 3 having theuneven surface can also be located on an end portion of the substrate 2.Still moreover, the vertical grooves 4 a are not always required to beformed at equal intervals, and this also applies to the horizontalgrooves 4 b. Still moreover, although the grooves 4 are formed such thatthe vertical grooves 4 a and the horizontal grooves 4 b are arranged tobe substantially orthogonal to each other, it is also acceptable thatgrooves formed along the first direction at equal or unequal intervalsand grooves formed along the second direction at equal or unequalintervals are arranged to obliquely cross each other at angles otherthan the right angle.

[0089] In addition, it is also possible to use only a single or pluralvertical grooves 4 a, or to use only a single or plural horizontalgrooves 4 b. Alternatively, it is also possible that grooves are formedin irregular directions at unequal intervals.

[0090] Still additionally, a luminescent device (structured lightingmaterial) 1′ shown in FIGS. 2(A) and 2(B) is also employable. Theluminescent device comprises a substrate 2, a luminescent unit 3 adheredon the substrate 2 and grooves 4′ formed in the luminescent unit 3. InFIG.2(A), the grooves 4′ comprises horizontal grooves 4 b′ arranged atequal intervals in vertical directions, with each of the horizontalgrooves 4 b′ formed to extend along the horizontal directions. Theluminescent unit 3 has a wave-like cross-sectional configuration asshown in FIG. 2(B), and the deepest portion thereof nearly reaches thesubstrate 2.

[0091] Besides such grooves, it is also acceptable that holes are madein the luminescent unit 3 at an equal or unequal intervals by means of asharp-edged tool. Many kinds of defects are made in the luminescent unit3 at random; grooves, holes and any other type of defects are made inthe luminescent unit 3 in a mixed state.

[0092] Furthermore, a description will be given hereinbelow of a methodto adhere phosphor powder to the substrate 2 for the formation of theluminescent unit 3 on the substrate 2. Among the adhesion methods, thereare settling coating, dusting, dip coating, deposition, ablation,sputtering, CVD, a painting method using a tool such as a brush, andothers.

[0093] A description will be given hereinbelow of an adhesion methodbased on settling coating using water-glass aqueous solution as binder(sticking agent) and an adhesion method based on dusting without binder.

[0094] First of all, the description starts at one example of settlingcoating using water-glass aqueous solution as binder. Ion exchange waterof 175 ml (milliliter) and high-concentration water-glass aqueoussolution (high-concentration potassium silicate aqueous solution) of 25ml are mixed with each other to produce water-glass aqueous solution,and this water-glass aqueous solution of 20 ml is put in a beaker with acapacity of 100 ml, and phosphor powder of 0.2945 g is additionally putin this beaker to produce a mixture of the water-glass aqueous solutionand the phosphor powder. An ultrasonic dispersion is conducted on thismixture solution of the water-glass aqueous solution and the phosphorpowder for 10 minutes.

[0095] Subsequently, barium acetate aqueous solution (0.05 wt %) of 25ml is put in the 100-ml beaker, and in a state where it is placed on analuminum plate, two substrates (bases) 2 (for example, made of copper)are dipped in the barium acetate aqueous solution within the beaker.Moreover, the water-glass aqueous solution containing the phosphorpowder (mixture solution of the water-glass aqueous solution and thephosphor powder) after the ultrasonic dispersion is put in the beakeraccommodating the substrates 2 and the barium acetate aqueous solutionwhile stirred. Still moreover, after the completion of the precipitationof the phosphor powder in the mixture solution of the barium acetateaqueous solution and the water-glass aqueous solution, the substrates 2,together with the aluminum plate, are removed from this mixturesolution, and the substrates 2 are dried in air for about one day. Thus,the phosphor powder is adhered onto the substrates 2 to form theluminescent units 3 on the substrates 2.

[0096] Secondly, a description will be given hereinbelow of a method ofadhering fine particles (phosphor powder) on the substrate 2 by means ofdusting without using binder. In this method, for example, after onesticking surface of an adhesive double coated tape is attached to asurface of the substrate 2, a phosphor powder is dusted on the othersurface of the adhesive double coated tape so that the phosphor powderis adhered through the adhesive double coated tape onto the substrate 2(the luminescent unit 3 is formed on the substrate 2).

[0097] The water-glass aqueous solution shows electrical conductiveproperty. Therefore if the water-glass aqueous solution is used asbinder, there is a possibility of degrading the non-electricalconductive property (deteriorating the electrification characteristic)of the luminescent unit 3, since the water-glass component is containedin the luminescent unit 3. So it is preferable that the dusting whichrequires no binder such as water-glass aqueous solution is used as amethod to adhere the phosphor powder on the substrate 2.

[0098] In this connection, the dusting does not always require the useof such an adhesive tape. It allows other adhesive (for example, bariumacetate aqueous solution) to be applied on to the substrate 2 beforepowder(phosphor powder)is dusted on the substrate 2 and dried.

[0099] A more specific example of the dusting will be described below. Apotassium silicate aqueous solution (concentration: 28.03 wt %, specificgravity: 1.244) is collected approximately two droplets (about 0.5 ml)by a dropping pipet and dropped on a copper-made substrate (28 mm×20 mm)plated with nickel. In addition, this copper-made substrate is dried inair for only two or three hours or is dried sufficiently through the useof a drier or the like. Following this, a barium acetate solution(concentration: 0.05 wt %) is taken approximately one droplet(approximately 0.2 ml) by a dropping pipet and is dropped on a portionof the substrate holding the potassium silicate aqueous solution appliedand dried.

[0100] This treatment produces sol-like silica on the substrate.Phosphor powder is dusted thereonto (dusting). In this case, it ispreferable that the dusting is conducted so that the weight density ofthe applied film becomes approximately 50 mg/cm² to 100 mg/cm². However,the weight density of the applied film is not limited to this. After thecoating of the phosphor powder, it is vacuum-dried, thereby realizing adusting-applied film.

[0101] Although the method to adhere phosphor powder onto the substrate2 is not limited to the above-mentioned methods, it is preferable toemploy a method of maintaining the non-electrical conductive property ofthe phosphor powder without providing the electrical conductive propertyfor easy electrification of the luminescent unit 3, such as theabove-mentioned dusting (including methods by which the luminescent unit3 can be easily electrified after the adhesion of the phosphor powder onthe substrate 2).

[0102] A luminescent device forming one embodiment of the structuredlighting material according to the present invention is fabricated asdescribed above. The inventors have found the following phenomena byforming a minute uneven surface structure non-uniform thickness, forexample, the grooves 4 are formed in the luminescent unit 3 with anon-electrical conductive property.

[0103] Thus, the intensity of luminescence outputted from theluminescent unit 3 increases superlinearly with respect to the input ofthe energy when the applied energy exceeds a threshold, and thisluminescent intensity is extremely higher as compared with aconventional luminescent device. Furthermore, depending on conditions,the luminescent color begins to vary around this threshold.

[0104] Since the luminescent state of the luminescent unit 3 stronglydepends on the magnitude of the inputted energy near the threshold, itis possible to visually detect the variance of the energy inputted tothe luminescent unit 3 around the threshold by monitoring theluminescent state (luminescent intensity or luminescent color) of theluminescent unit 3 with this luminescent device. This enables theluminescent device to be used for detectors or alarms.

[0105] In addition, since the luminescent state of the luminescent unit3 shows rapid variation around the threshold, the variation of theluminescent state near the threshold can be used as on/off signal, andis applicable to memories or various types of control device.

[0106] Still additionally, since higher luminescent intensity isobtainable as compared with that of the conventional element, anilluminator such as a high-efficient illuminating apparatus is feasible.As the illuminator, the structured lighting material according to thepresent invention is applicable to display tubes (such as image tubesand cathode-ray lamps which will be described later as applicationexamples) as well as indoor illumination, projectors, back lights, andso forth.

[0107] In any case, this luminescent device can provide useful effectsin a wide range of applications owing to its rapid variation of theluminescent state and its high-efficiency. Thus it is a significantinvention. Moreover, since the present invention requires only a minuteuneven surface of the luminescent unit formed by making simple grooveson the convention luminescent device, this permits the utilization ofthe conventional manufacturing processes for the luminescent devices.Various kinds of knowledge and experience on the conventionalluminescent device can be applied to the product of the currentinvention.

[0108] The structured lighting material (luminescent device) accordingto the present invention is not limited to the above-describedembodiments, and covers all changes and modifications of the embodimentsof the invention herein which do not deviate from the spirit and scopeof the invention.

[0109] For example, although the grooves 4 are made over the entire areaof the luminescent unit 3 in the above-described embodiments, it is alsoappropriate that the grooves 4 are made in a portion of the luminescentunit 3. Also in this case, in the groove made area of the luminescentunit 3, the luminescent state changes suddenly around a threshold of theinput energy.

[0110] Incidentally, in the above-described embodiments, a luminescentunit with a structured lighting material according to the presentinvention is composed of phosphor, it is also possible to use otherorganic and/or inorganic material.

EXAMPLES

[0111] Referring to the drawings, a further description will be given indetail hereinbelow of examples of the structured lighting materialsaccording to the present invention. FIGS. 3 to 8 are illustrations ofluminescent devices according to the examples and conventionalluminescent devices used as comparative examples. In FIGS. 4, 5, 7 and8, dots represent the actually measured values, and a current dependencycurve of the luminescent intensity is drawn by smoothly connecting thesedots. Moreover, FIGS. 1(A) and 1(B) used for the description of theabove embodiments and FIGS. 11(A) and 11(B) for the description of theconventional technique will also be used for the following description.Incidentally, the structured lighting material according to the presentinvention is not limited to the examples as disclosed in the below.

(A) First Example

[0112] A luminescent device 1A according to this example of the presentinvention was, as well as the luminescent device 1 according to theabove-described embodiment, composed of a substrate 2, a luminescentunit 3 formed on the substrate 2 and lattice-like grooves 4 formed inthe luminescent unit 3 as shown in FIGS. 1(A) and 1(B). The substrate 2was made of a copper plate, and the luminescent unit 3 was formed on thesubstrate 2 in a manner that red phosphor (Y₂O₂S: Eu, Tb) powder fortelevisions was settling-coated in water-glass aqueous solution and thendried sufficiently.

[0113] The lattice-like grooves 4 were made in a state where verticalgrooves 4 a and horizontal grooves 4 b were arranged at equal intervals(for example, 1 mm). The grooves 4 a and 4 b were made by scratching theluminescent unit 3 with a sharp-edged tool such as a tip portion of apincette.

[0114] According to the results of measurement by a non-contact typethree-dimensional analysis apparatus, various kinds of parameters ofminute uneven surface were such that the maximum thickness was in arange from 200 μm to 500 μm while the minimum thickness was in a rangefrom 20 μm to 50 μm, and the inclination angle of the uneven surfaceranged from 50 degrees to 88 degrees.

[0115] A luminescent device 101A with a conventional fabrication wasproduced as a comparative example to the luminescent device 1A. Thisluminescent device 101A with the conventional fabrication was made tohave the same configuration as that of the luminescent device 1A exceptthat the grooves 4 were not made therein, and the manufacturing methodthereof was the same as the method for the luminescent device 1A, butwith no procedure for the formation of the grooves 4. That is, thisluminescent device 101A with the conventional fabrication was made up ofa copper-made substrate 102 and a luminescent unit 103 form on thesubstrate 102 as shown in FIGS. 11(A) and 11(B), and the luminescentunit 103 was formed in a manner that television red phosphor (Y₂O₂S: Eu,Tb) powder was settling-coated on the substrate 102 in water-glassaqueous solution.

[0116] The current dependency of luminescent intensity was measured onthe luminescent device 1A according to the example of this invention andthe conventional luminescent device 101A using an experimental equipment50 shown in FIG. 3.

[0117] A description will be given hereinbelow of this experimentalequipment 50. As FIG. 3 shows, the experimental equipment 50 is made upof a vacuum device 51 accommodating the samples (the luminescentdevices) 1A and 101A being measured and placed internally in asubstantial vacuum condition, an electron gun 52 for applying anelectron beam to the samples measured in the vacuum device 51, ahigh-voltage power supply 53 for supplying high-voltage power to theelectron gun 52, a sputter ion pump 54A and turbo-molecular pump 54B formaking the interior of the vacuum device 51 vacuous (up to 1×10⁻⁵ Pa),and an observation window or port 55 for observation of the interior ofthe vacuum device 51. The observation window 55 is also used as an entrythrough which an electron beam evaluation device 56 or a luminescentspectrometer (not shown) is inserted into the interior of the vacuumdevice 51.

[0118] In this equipment 50, first, after the luminescent device 1A and101A are set in the interior of the vacuum device 51, the sputter ionpump 54A and the turbo-molecular pump 54B are properly manipulated sothat the interior of the vacuum device 51 forms a vacuum below asufficient degree of vacuum (for example, 1×10⁻⁵ Pa). In addition, thehigh-voltage power supply 53 is actuated to apply electron beam from theelectron gun 52 to the luminescent device 1A and 101A in the interior ofthe vacuum device 51, and the current dependency of luminescentintensity of each of the luminescent device 1A and 101A is measured withthe electron beam evaluation equipment 56.

[0119]FIG. 4 is a log-log graph where the vertical axis representsluminescent intensity I of a luminescent device and the horizontal axisdenotes beam current (current value) A fed to the electron gun 52 (thatis, energy applied to the luminescent device 1A or 101A). In theconventional luminescent device 101A, as denoted by circled numeral 1 inFIG. 4, the luminescent intensity I increased monotonically withincrease in beam current A until the beam current A approachesapproximately 30 μA, while the luminescent intensity I decreased whenthe beam current A exceeded 30 μA.

[0120] The luminescent intensity I of this luminescent device 1A isdenoted by circled numeral 2 in FIG. 4. The luminescent intensity I ofthis luminescent device 1A increased monotonically with an increase inthe beam current A until the beam current A goes to the vicinity of the20 μA just as the conventional luminescent device 101A does. When thebeam current A exceeded approximately 20 μA, the increase tendencythereof went upward rapidly so that the luminescent intensity increasedsuperlinearly to reach an extremely high value. This result was contraryto the case of the conventional luminescent device 101A.

[0121] This demonstrated that, if the grooves 4 are made in theluminescent unit 3 so that the luminescent unit 3 has a minute unevensurface non-uniform in thickness, the luminescent intensity I increasessuperlinearly when the beam current A exceeds a threshold A₀ (in thiscase, approximately 20 μA), and an output can be higher than that of theconventional luminescent device 101A.

[0122] When the beam current A is below the threshold A₀, theluminescent intensity I of this luminescent device 1A is lower than thatof the conventional luminescent device 101A. This is because the area ofthe luminescent unit 3 of the luminescent device 1A, including thegrooves 4, is made to be equal to the area of the luminescent unit 103of the conventional luminescent device 101A; the luminescent device 1Ahas a smaller luminescence area of the luminescent unit 3 than that ofthe conventional luminescent device 101A by area corresponding to thegrooves 4.

(B) Second Example

[0123] In this example, a luminescent device 1B (having grooves 4)according to the second example of the present invention and aluminescent device 101B with a conventional fabrication (having nogrooves) were prepared. Here, blue phosphor (SrHfO₃: Tm) inventedpreviously was used for the luminescent device 1B and 101B.

[0124] The luminescent device 1B is made up of a copper-made substrate2, a luminescent unit 3 and lattice-like grooves 4 as well as theabove-mentioned luminescent device 1A according to the first example asshown in FIGS. 1(A) and 1(B). The luminescent unit 3 was made on thesubstrate 2 with the blue phosphor (SrHfO₃:Tm) powder beingsettling-coated in water-glass aqueous solution.

[0125] The luminescent device 101B is composed of a copper-madesubstrate 102 and a luminescent unit 103 formed by settling-coating bluephosphor (SrHfO₃:Tm) powder onto the substrate 102 in water-glassaqueous solution.

[0126] The blue phosphor (SrHfO₃:Tm) powder synthesis is feasibleaccording to the methods disclosed in Japanese Patent Laid-Open Nos. HEI8-283713, 10-121041 and 10-121043.

[0127] Usually, for the blue phosphor (SrHfO₃:Tm) powder synthesis, Sr(strontium) oxide, hydroxide, carbonate or nitrate, Hf (hafnium) oxideand others were weighed for a quantity and intermixed sufficiently, andin a heat resistance vessel such as a crucible, this mixture was firedonce or more times at a temperature of 800 to 1600° C. for one to twelvehours in air or in oxidation atmosphere.

[0128] Specifically, in this case, the blue phosphor powder synthesiswas conducted as follows.

[0129] As raw materials, there were prepared SrCO₃ (4N), HfO₂ (3N) andTm₂O₃ (powder 3N) or Tm(NO₃)₃ (solution, 3N). In addition, alkali metalchloride (carbonate, nitrate or the like) is used as flux, and in thiscase, Na₂CO₃ (4N) was prepared by 10 mol % of a phosphor to be produced.The numerals in parentheses represent purities.

[0130] Moreover, these are weighed in stoichiometric ratio andwet-blended in a mortar. And in a heat resistance vessel such as analumina crucible, this mixture was fired at a temperature of 1600° C.for four or five hours in air or in oxidation atmosphere. Then,grinding, washing, drying and sieving were conducted on this firedmaterial for the powder synthesis of the blue phosphor (SrHfO₃:Tm) afterremoval of coarse particles.

[0131] The luminescent device 1B (the luminescent device 101B) was setin the equipment 50 shown in FIG. 3. The current dependency ofluminescent intensity was measured on the luminescent device 1B and 101Bwith the electron beam evaluation equipment 56. The luminescent spectrumwas measured by the luminescent spectrometer. FIG. 5 shows the resultsof measurement of the current dependency of luminescent intensity. FIG.6 shows the results of measurement of luminescent spectrum. For themeasurement of luminescent spectrum, the luminescent spectrometer (notshown) is set in place of the electron beam evaluation equipment 56.

[0132] First, a description will be given hereinbelow of the results ofmeasurement of the current dependency of luminescent intensity. In alog-log graph of FIG. 5, the vertical axis represents luminescentintensity I of a luminescent device while the horizontal axis denotes abeam current A supplied to the electron gun 52. In the luminescentdevice 101B having no groove, as denoted by circled numeral 3 in FIG. 5,the luminescent intensity I increased monotonically with an increase inthe beam current A until the beam current A approaches approximately 30μA. When the beam current A became above approximately 30 μA, theincrease tendency thereof went downward, and when the beam current Aexceeds approximately 100 μA, the luminescent intensity I fell into asaturated condition.

[0133] On the other hand, in this luminescent device 1B having thegrooves 4, as denoted by circled numeral 4 in FIG. 5, the luminescentintensity I increased monotonically until the beam current A increasedup to approximately 100 μA. When the beam current A exceededapproximately 100 μA, the increase tendency thereof went upward rapidlyand the luminescent intensity I increased superlinearly. In other words,the luminescent intensity I increased superlinearly when the beamcurrent A exceeded this threshold A₀ (in this case, approximately 100 A)contrary to that of the conventional luminescent device 101A.

[0134] Secondly, a description will be given hereinbelow of the resultsof measurement of luminescent spectrum. FIG. 6 shows a luminescentspectrum of the luminescent device 1B in a case when a beam current Alarger than the threshold A₀ is supplied to the electron gun 52; thehorizontal axis represents a wavelength λ [nm] of the luminescence andthe vertical axis denotes a luminescent intensity I.

[0135] As FIG. 6 shows, the luminescent intensity I shows a peak(luminescent peak) S1 in the vicinity of 450 nm. This luminescent peakS1 corresponds to a blue luminescent band stemming from f-f transitionsof Tm forming the luminescence center of a blue phosphor (SrHfO₃:Tm)constituting the luminescent unit 3. Thus luminescent peak S1 appears inthis luminescent device 1B even when the beam current A is below thethreshold A₀. Also in the luminescent device with the conventionalfabrication, this peak S1 was observed.

[0136] However, in this luminescent device 1B, when the beam current Aexceeded the threshold A₀, a new luminescent band S2 ranged from 500 nmto 1200 nm in wavelength λ as well as the blue luminescent band S1 wereobserved (FIG. 6), the resultant luminescent color thus turned to white.

[0137] Accordingly, from this measurement, it was demonstrated that, ifthe grooves 4 are formed in the luminescent unit 4 so that theluminescent unit 3 has a minute uneven configuration in thickness, theluminescent intensity I increases superlinearly and the luminescentcolor varies (in this case, varies from blue to white) when the beamcurrent A exceeds the threshold A₀.

(C) Third Example

[0138] In a third example of the present invention, a luminescent device1C was made up of a copper-made substrate 2, a luminescent unit 3 formedon the substrate 2 by the dusting of phosphor powder and lattice-likegrooves 4 made in the luminescent unit 3 as shown in FIGS. 1(A) and1(B); blue phosphor (SrHfO₃: Tm) powder that contains KCl of 10 mol %acting as flux was used as the phosphor powder. FIG. 7 shows the currentdependency of the luminescent intensity of the luminescent device 1Cmeasured with the experimental equipment 50 shown in FIG. 3.

[0139] In a log-log graph of FIG. 7, the vertical axis representsluminescent intensity I of a luminescent device and the horizontal axisdenotes beam current A to be supplied to the electron gun 52.

[0140] In the luminescent device 1C according to this example, as FIG. 7shows, the intensity I monotonically increased until the beam currentincreased up to threshold (about 101A). The luminescent intensity I oncedropped when the beam current A exceeds the threshold A₀. Theluminescent intensity I increased superlinearly at an increase tendencygreater than that below the threshold A₀.

[0141] In the luminescent device 1C according to this example, thethreshold A₀ is approximately 10 μA, which was a lower value than thethresholds A₀ of the luminescent devices 1A and 1B according to theabove-described examples. The reason of the lower threshold A₀ can beassumed as follows.

[0142] The above-mentioned superlinear rise of the luminescent intensitywas observed when the energy applied to the luminescent device exceededa threshold. This can be enhanced by electrification property of theluminescent unit 3. In the luminescent device according to the presentinvention, non-electrical conductive phosphor powder is employed formaking the luminescent unit 3 acquire the electrification property,while in the luminescent devices 1A and 1B according to theabove-described examples, water glass with electrical-conductiveproperty is used as binder for the formation of the luminescent unit 3on the substrate 2; therefore, the non-electrical conductive property ofthe luminescent unit 3 containing the water glass is impaired tosomewhat diminish the electrification property thereof. On the otherhand, in the case of this third example, since the luminescent unit 3 isproduced by the dusting instead of the use of the water glass, it can beunderstood that the non-electrical conductive property is improved. Thusit was observed that the superlinear rise of the luminescent intensityat lower beam current A than those of the luminescent devices 1A and 1Baccording to the above-described examples.

(D) Comparative Examples

[0143] Besides the above-described first and second examples, anexperiment was performed with a phosphor ZnO. ZnO has electricalconductive property (estimated electrical resistivity is 10 to 300 Ω·cm)in the form of phosphor powder and put on the market.

[0144] As shown in FIGS. 1(A) and 1(B), the phosphor powder ZnO wascoated by sedimentation on a copper-made substrate 2 in water-glassaqueous solution and dried sufficiently to form powder layer(luminescent unit) 3 on the substrate 2. For producing a luminescentdevice ID, lattice-like grooves 4 were made in the powder layer 3 at aninterval of 1 mm with a sharp-edged tool such as a pincette. Inaddition, as FIGS. 11(A) and 11(B), phosphor powder ZnO was coated bysedimentation on a substrate 1 in water-glass aqueous solution and driedsufficiently to form powder layer (luminescent unit) 3 on the substrate2, thereby producing a luminescent device 101D with conventionalfabrication.

[0145] The luminescent intensity under the bombardment of electron beamcurrent was measured for these luminescent device 1D and 101D, throughthe use of the experimental equipment 50 shown in FIG. 3. The resultsare shown in FIG. 8.

[0146] In the log-log graph of FIG. 8, the vertical axis representsluminescent intensity I of the luminescent device and the horizontalaxis denotes beam current A supplied to the electron gun 52. In theillustrations, circled numeral 6 is for the luminescent device 1D(having grooves) and circled numeral 5 is for the luminescent device101D (without grooves).

[0147] As obvious from FIG. 8, the luminescent intensity I showed amaximum value in the vicinity of beam current A of 100 μA, and theluminescent intensity I decreased beyond the beam current A. This wasirrespective of the presence (the luminescent device 1D) or absence(luminescent device 101D) of grooves. In case the luminescent unit wasfabricated with an electrical conductive phosphor, the luminescentintensity I thus did not increase superlinearly even if the beam currentA increased beyond a threshold. The effect of the grooves 4 was notobtained.

[0148] It can be understood that this is because the powder (phosphor)itself has electrical conductive property to acquire lesselectrification property even if the grooves 4 are made in theluminescent unit 3 so that the luminescent unit 3 has minute unevensurface for facilitating the storage of electric charge. This supportedthe inventors' concept that the electrification property of theluminescent unit 3 is related to the above-mentioned phenomenon (thephenomenon that the luminescent intensity I increases superlinearly withthe beam current A above a threshold, as observed in the threeexamples).

(E) First Application Example

[0149] Referring to the drawings, a description will be givenhereinbelow of an application example in which a structured lightingmaterial according to the present invention is incorporated into animage tube forming a luminescent display (illuminator). FIG. 9 is anillustrative view showing a configuration of the image tube as the firstapplication example of the structured lighting material according to thepresent invention.

[0150] As FIG. 9 shows, a face glass 62 is fixedly adhered onto acylindrical glass vessel 61 to produce a vacuum vessel (envelop) 63 inthis image tube. In addition, in the interior of the vacuum vessel(envelope) 63, there are a luminescent surface (luminescent unit) 64, ananode electrode (substrate) 65 and a cathode forming a electrondischarge unit (a grid 66, a cathode 67). A structured lighting materialaccording to the present invention is applied to the aforesaidluminescent surface 64 and anode electrode 65.

[0151] In general, the anode electrode 65 is composed of a metallicelectrode made of aluminum, copper or the like, or a metal platedelectrode made of these metals. The cathode 67 of the electron dischargesection is typically a conventional filament (for example, made byapplying electron-emissive material like barium oxide/calciumoxide/strontium oxide to the tungsten filament), carbon nanotube or thelike.

[0152] In this image tube, a voltage is applied to the grid 66 toestablish a condition of electron discharge from the electrode 67. Inaddition, when a electric potential works on the anode electrode 65 andthe electrons discharged from the cathode 67 are accelerated to collideagainst and penetrate the anode electrode 65, thereby making impact onthe luminescent surface 64. As a result, the luminescent surface 64 isexcited by the electron impact and luminescent color corresponding tothe luminescent material forming the luminescent surface 64 passesthrough the face glass 62 and appears as luminescence 68 on the frontside.

(F) Second Application Example

[0153] Referring to the drawings, a description will be givenhereinbelow of an example of the application of a structured lightingmaterial according to the present invention applied to a cathode-rayluminescent lamp. FIG. 10 is an illustrative view showing aconfiguration of a cathode-ray luminescent lamp as the second example ofthe application of a structured lighting material according to thepresent invention.

[0154] As FIGS. 10(A) and 10(B) show, in this cathode-ray luminescentlamp, a vacuum vessel (envelope) 63A is composed of a cylindrical glassvessel 61A and a face glass 62A. In addition, in the interior of thevacuum vessel (envelope) 63A, there are a luminescent surface(luminescent unit) 64A, an anode electrode (substrate) 65A and a cathodeforming a electron discharge section (a grid 66A, a cathode 67A). Astructured lighting material according to the present invention isincorporated into the aforesaid luminescent surface 64A and anodeelectrode 65A.

[0155] In general, the anode electrode 65A is composed of a metallicelectrode made of aluminum, copper or the like, or a metal platedelectrode made of these metals. The cathode 67A of the electrondischarge section is typically a conventional filament (for example,made by applying electron-emissive material like barium oxide/calciumoxide/strontium oxide to a tungsten filament), a carbon nanotube or thelike.

[0156] In this cathode-ray luminescent lamp, a voltage is applied to thegrid 66A to make a condition of electron discharge from the electrode67A. In addition, when a electric potential works on the anode electrode65A and the electrons discharged from the cathode 67A are acceleratedtoward the anode electrode 65A to collide against the luminescentsurface 64A so that an impact takes place thereon. As a result, theluminescent surface 64A is excited by the electron impact andluminescent color corresponding to the luminescent material forming theluminescent surface 64A passes through the face glass 62A andluminescence takes place toward the front side.

[0157] As mentioned above, in the first and second application examples,the luminescent surfaces 64 and 64A are made up of the structuredlighting material with an uneven surface of luminescent unit. Thus,according to the above-mentioned application examples, the configurationof the structured lighting material, specifically the formation of theminute uneven surface of the luminescent unit (coated layer), realizes ahigh-efficient illuminator such as an image tube or a cathode-rayluminescent lamp.

[0158] In this connection, although the above-mentioned applicationexamples relate to the image tube and the cathode-ray luminescent lamp,the present invention covers all changes and modifications of theapplication examples which do not deviate from the spirit and scope ofthe invention. For example, in the image tube according to the firstapplication example shown in FIG. 9, it is also possible that the anodeelectrode 65 and the luminescent surface 64 are reversed in positionalrelationship so that the direction of the luminescence is toward thecathode side. It is also acceptable to construct it without the grid 66.

What is claimed is:
 1. A structured lighting material comprising aluminescent unit wherein the intensity of its incoherent luminescenceincreases superlinearly when energy applied in a non-contact mannerexceeds a threshold.
 2. A structured lighting material according toclaim 1, wherein the luminescent color of said luminescent unit changeswhen said energy exceeds said threshold.
 3. A structured lightingmaterial according to claim 1, wherein said energy is electric energyoriginating from any 3 one of electron beam, electric charge andelectric field.
 4. A structured lighting material according to claim 1,wherein said luminescent unit has non-electrical conductive property. 5.A structured lighting material comprising a luminescent unit which showsnon-electrical conductive property and has a minute uneven surface ofwhich luminescent intensity increases superlinearly when energy appliedto said minute uneven surface in a non-contact manner exceeds athreshold.
 6. A structured lighting material according to claim 5,wherein said minute uneven surface is formed in a manner that saidluminescent unit is formed to be non-uniform in thickness.
 7. Astructured lighting material according to claim 6, wherein said minuteuneven surface has high and low portions respectively corresponding tomaximum and minimum thicknesses of said luminescent unit, and saidmaximum thickness is set to be three or more times said minimumthickness.
 8. A structured lighting material according to claim 6,wherein said minute uneven surface has high and low portionsrespectively corresponding to maximum and minimum thicknesses of saidluminescent unit, and said maximum thickness is set to be ten or moretimes said minimum thickness.
 9. A structured lighting materialaccording to claim 6, wherein said minimum thickness of said luminescentunit is not more than 500 μm.
 10. A structured lighting materialaccording to claim 6, wherein said minimum thickness of said luminescentunit is not more than 50 μm.
 11. A structured lighting materialaccording to claim 6, wherein an inclination angle of the minute unevensurface is in a range from 30 degrees to 150 degrees.
 12. A structuredlighting material according to claim 6, wherein an inclination angle ofthe minute uneven surface is in a range from 50 degrees to 130 degrees.13. A structured lighting material according to claim 1, wherein saidluminescent unit is made of inorganic material.
 14. A structuredlighting material according to claim 1, wherein said luminescent unit isadhered on a substrate.
 15. A structured lighting material according toclaim 14, wherein said luminescent unit is adhered on said substratewithout water-soluble fixing agent.
 16. A structured lighting materialaccording to claim 15, wherein said luminescent unit is adhered on saidsubstrate in a manner of facilitating electrification.
 17. Anilluminator using said structured lighting material defined in claim 1.18. An illuminator using said structured lighting material defined inclaim
 5. 19. A method to generate incoherent luminescence of which theluminescent intensity increases superlinearly when applied energy in anon-contact manner exceeds a threshold.